WO1999044264A1 - Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz - Google Patents

Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz Download PDF

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Publication number
WO1999044264A1
WO1999044264A1 PCT/IL1998/000092 IL9800092W WO9944264A1 WO 1999044264 A1 WO1999044264 A1 WO 1999044264A1 IL 9800092 W IL9800092 W IL 9800092W WO 9944264 A1 WO9944264 A1 WO 9944264A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
chamber
loops
axis
laser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IL1998/000092
Other languages
English (en)
Inventor
Victor Isaevich Adamovski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Motors Engineering Ak Ltd
Original Assignee
Motors Engineering Ak Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Motors Engineering Ak Ltd filed Critical Motors Engineering Ak Ltd
Priority to PCT/IL1998/000092 priority Critical patent/WO1999044264A1/fr
Publication of WO1999044264A1 publication Critical patent/WO1999044264A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/03—Constructional details of gas laser discharge tubes
    • H01S3/032—Constructional details of gas laser discharge tubes for confinement of the discharge, e.g. by special features of the discharge constricting tube
    • H01S3/0326—Constructional details of gas laser discharge tubes for confinement of the discharge, e.g. by special features of the discharge constricting tube by an electromagnetic field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/097—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser
    • H01S3/0975—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser using inductive or capacitive excitation

Definitions

  • the present invention relates to lasers and, more particularly, to a gas laser of improved efficiency.
  • Figure 1 is a partial schematic cross-section of a typical gas laser 10.
  • a hermetically sealed cylindrical chamber 12 contains a gas 14 such as carbon dioxide under low pressure.
  • the longitudinal axis of chamber 12 is represented by a dashed line 16.
  • Ends 18 of chamber 12 are transparent to the stimulated radiation emitted by gas 14.
  • Two mirrors (not shown) are provided beyond ends 18. These two mirrors define between them a laser cavity.
  • Gas laser 10 also includes means for exciting gas 14 energetically, thereby inducing the stimulated emission of radiation by gas 14. Two such means are shown in Figure 1. One is a pair of electrodes 20, within chamber 12, between which an arc discharge is created to heat gas 14. The other is a solenoid 22, outside of chamber 12 and concentric with axis 16, by means of which an RF electromagnetic field is created within chamber 12, typically at frequencies between 8 KHz and 20 KHz..
  • High energy gas lasers typically have efficiencies on the order of 5%.
  • a typical high energy carbon dioxide laser is driven by 190 kilowatts of power but emits coherent radiation having a power of only 9 kilowatts.
  • electrodes 20 create a plasma within chamber 12 that is much hotter near axis 16 than near the walls of chamber 12.
  • Solenoid 22 creates a plasma within chamber 12 whose region of maximum temperature is an annular region concentric with axis 16 but closer to the walls of chamber 12 than to axis 16.
  • the radiative transitions of the molecules of gas 14 that are the source of the emitted radiation occur predominantly in parts of the plasma that are cooler than the maximum temperature.
  • the active part of the plasma is near the walls of chamber 12.
  • the active part of the plasma is concentrated around axis 16. As a result, only about 20% to 30% of the volume of gas 14 participates in the emission of radiation.
  • a method for increasing the efficiency of a gas laser in which stimulated emission of radiation is induced in a gas contained in a chamber having an axis, the gas thereby becoming at least partially ionized comprising the step of electromagnetically stirring the ionized gas.
  • the present invention is based on the fact that a plasma, being an ionized gas, interacts strongly with a magnetic field.
  • a time- varying electromagnetic field is imposed on the plasma to stir and mix it, thereby creating a uniform temperature distribution in the plasma.
  • this is accomplished by encircling chamber 12 with loops of electrically conductive wire that are tilted with respect to axis 16, and pulsing electrical current through the loops.
  • FIG. 1 (prior art) is a partial schematic cross section through a gas laser
  • FIG. 2 is a partial perspective view of a gas laser according to the present invention.
  • FIG. 3 is a partial perspective view of another gas laser according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • the present invention is of a gas laser whose plasma has a relatively uniform operating temperature distribution. Specifically, the plasma is stirred and mixed electromagnetically.
  • Figure 2 is a perspective exterior view of chamber 12 equipped with three planar circular loops 32, 34 and 36 of electrically conductive wire that encircle chamber 12.
  • the planes of loops 32, 34 and 36 are tilted at an acute angle with respect to axis 16.
  • Loops 32, 34 and 36 are distributed around chamber 12 at uniform azimuthal spacings of 120°. Pulses of electrical current are provided to loops 32, 34 and 36, preferably at a frequency of between about 50 Hz and about 1000 Hz, to create a helical magnetic field within chamber 12 that keeps the plasma inside chamber 12 uniformly mixed.
  • the axis of the chamber is defined by the means used to create the plasma that is mixed by the time-varying electromagnetic field of the present invention.
  • axis 16 is defined as running between electrodes 20.
  • RF field created by solenoid 22 If gas 14 is excited by an RF field created by solenoid 22, then axis 16 is the axis of solenoid 22.
  • Figure 3 is a partial perspective view of a high-power carbon dioxide laser 40.
  • Two RF transmitters 42 define between them a chamber 44 through which carbon dioxide gas is caused to flow, from an inlet 50 to an outlet 52.
  • RF transmitters 42 by defining between them chamber 44, also define between them axis 46.
  • RF transmitters 42 and chamber 44 defined therebetween are encircled by three planar loops of electrically conductive wire, tilted at an acute angle with respect to axis 46.
  • reference numeral 60 For clarity, only one of the loops, designated by reference numeral 60, is shown in Figure 3.
  • the present invention has the further advantage of reducing the power required to excite the plasma.
  • each pulse must be sufficiently energetic to heat gas 14 to its centrally peaked operating temperature profile. If coils 32, 34 and 36 are used to stir the plasma electromagnetically, then pairs of lower energy pulses may be used to heat gas 14, with the first pulse heating gas 14 part of the way to its flat operating temperature profile, and the second pulse completing the heating.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

La chambre à plasma (12) d'un laser à gaz est encerclée de boucles de fil conducteur (32, 34, 36). Des impulsions de courant électrique dans les boucles créent des champs magnétiques variant dans le temps qui agitent le plasma et assurent une répartition uniforme de sa température.
PCT/IL1998/000092 1998-02-25 1998-02-25 Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz Ceased WO1999044264A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IL1998/000092 WO1999044264A1 (fr) 1998-02-25 1998-02-25 Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IL1998/000092 WO1999044264A1 (fr) 1998-02-25 1998-02-25 Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz

Publications (1)

Publication Number Publication Date
WO1999044264A1 true WO1999044264A1 (fr) 1999-09-02

Family

ID=11062316

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IL1998/000092 Ceased WO1999044264A1 (fr) 1998-02-25 1998-02-25 Laser a gaz muni de boucles creant un champ magnetique pour agiter le gaz

Country Status (1)

Country Link
WO (1) WO1999044264A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3681710A (en) * 1971-05-21 1972-08-01 United Aircraft Corp Gas laser
US3824492A (en) * 1972-06-22 1974-07-16 United Aircraft Corp Solid state single frequency laser
US4802184A (en) * 1986-01-29 1989-01-31 Fanuc Ltd High frequency discharge excited coaxial type CO2 laser

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3681710A (en) * 1971-05-21 1972-08-01 United Aircraft Corp Gas laser
US3824492A (en) * 1972-06-22 1974-07-16 United Aircraft Corp Solid state single frequency laser
US4802184A (en) * 1986-01-29 1989-01-31 Fanuc Ltd High frequency discharge excited coaxial type CO2 laser

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